.a{
  .navbar {
    background: url('https://img1.baidu.com/it/u=1319713773,2074606622&fm=253&fmt=auto&app=138&f=JPG?w=889&h=500') !important;
  }
  .sidebar-container {
    background: url('https://img0.baidu.com/it/u=3904739651,825448990&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=649') !important;
  }
  
}
.b{
  .navbar {
    background: url('https://img2.baidu.com/it/u=555227454,1852482860&fm=253&fmt=auto&app=138&f=JPEG?w=658&h=388')!important;
  }
  .sidebar-container {
    background: url('https://img1.baidu.com/it/u=3912439866,2222493431&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=666') !important;
  }
}
.c{
  .navbar {
    background: url('https://img1.baidu.com/it/u=940649905,3273299746&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=889')!important;
  }
  .sidebar-container {
    background: url('https://img1.baidu.com/it/u=3407815955,2052996205&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=500')!important;
  }
}